OpenRaiser/Intern-Atlas huggingface dataset:
Sleep Period Optimization Model For Layered Video Service Delivery Over eMBMS Networks
Venue: arXiv cs.NI 2015
Year: 2015

Long Term Evolution-Advanced (LTE-A) and the evolved Multimedia Broadcast Multicast System (eMBMS) are the most promising technologies for the delivery of highly bandwidth demanding applications. In this paper we propose a green resource allocation strategy for the delivery of layered video streams to users with different propagation conditions. The goal of the proposed model is to minimize the user energy consumption. That goal is achieved by minimizing the time required by each user to receive the broadcast data via an efficient power transmission allocation model. A key point in our system model is that the reliability of layered video communications is ensured by means of the Random Linear Network Coding (RLNC) approach. Analytical results show that the proposed resource allocation model ensures the desired quality of service constraints, while the user energy footprint is significantly reduced.
Reducing overheads of dynamic scheduling on heterogeneous chips
Venue: arXiv cs.DC 2015
Year: 2015

In recent processor development, we have witnessed the integration of GPU and CPUs into a single chip. The result of this integration is a reduction of the data communication overheads. This enables an efficient collaboration of both devices in the execution of parallel workloads. In this work, we focus on the problem of efficiently scheduling chunks of iterations of parallel loops among the computing devices on the chip (the GPU and the CPU cores) in the context of irregular applications. In particular, we analyze the sources of overhead that the host thread experiments when a chunk of iterations is offloaded to the GPU while other threads are executing concurrently other chunks on the CPU cores. We carefully study these overheads on different processor architectures and operating systems using Barnes Hut as a study case representative of irregular applications. We also propose a set of optimizations to mitigate the overheads that arise in presence of oversubscription and take advantage of the different features of the heterogeneous architectures. Thanks to these optimizations we reduce Energy-Delay Product (EDP) by 18% and 84% on Intel Ivy Bridge and Haswell architectures, respectively, and by 57% on the Exynos big.LITTLE.
Unravelling the Impact of Temporal and Geographical Locality in Content Caching Systems
Venue: arXiv cs.NI 2015
Year: 2015

To assess the performance of caching systems, the definition of a proper process describing the content requests generated by users is required. Starting from the analysis of traces of YouTube video requests collected inside operational networks, we identify the characteristics of real traffic that need to be represented and those that instead can be safely neglected. Based on our observations, we introduce a simple, parsimonious traffic model, named Shot Noise Model (SNM), that allows us to capture temporal and geographical locality of content popularity. The SNM is sufficiently simple to be effectively employed in both analytical and scalable simulative studies of caching systems. We demonstrate this by analytically characterizing the performance of the LRU caching policy under the SNM, for both a single cache and a network of caches. With respect to the standard Independent Reference Model (IRM), some paradigmatic shifts, concerning the impact of various traffic characteristics on cache performance, clearly emerge from our results.
Confidential Algorithm for Golden Cryptography Using Haar Wavelet
Venue: arXiv cs.CR 2015
Year: 2015

One of the most important consideration techniques when one want to solve the protecting of digital signal is the golden matrix. The golden matrices can be used for creation of a new kind of cryptography called the golden cryptography. Many research papers have proved that the method is very fast and simple for technical realization and can be used for cryptographic protection of digital signals. In this paper, we introduce a technique of encryption based on combination of haar wavelet and golden matrix. These combinations carry out after compression data by adaptive Huffman code to reduce data size and remove redundant data. This process will provide multisecurity services. In addition Message Authentication Code (MAC) technique can be used to provide authentication and the integrity of this scheme. The proposed scheme is accomplished through five stages, the compression data, key generation, encryption stage, the decryption stage and decompression at communication ends.
Privacy and Data Protection by Design - from policy to engineering
Venue: arXiv cs.CR 2015
Year: 2015

Privacy and data protection constitute core values of individuals and of democratic societies. There have been decades of debate on how those values -and legal obligations- can be embedded into systems, preferably from the very beginning of the design process. One important element in this endeavour are technical mechanisms, known as privacy-enhancing technologies (PETs). Their effectiveness has been demonstrated by researchers and in pilot implementations. However, apart from a few exceptions, e.g., encryption became widely used, PETs have not become a standard and widely used component in system design. Furthermore, for unfolding their full benefit for privacy and data protection, PETs need to be rooted in a data governance strategy to be applied in practice. This report contributes to bridging the gap between the legal framework and the available technological implementation measures by providing an inventory of existing approaches, privacy design strategies, and technical building blocks of various degrees of maturity from research and development. Starting from the privacy principles of the legislation, important elements are presented as a first step towards a design process for privacy-friendly systems and services. The report sketches a method to map legal obligations to design strategies, which allow the system designer to select appropriate techniques for implementing the identified privacy requirements. Furthermore, the report reflects limitations of the approach. It concludes with recommendations on how to overcome and mitigate these limits.
A Polynomial-Time Attack on the BBCRS Scheme
Venue: arXiv cs.CR 2015
Year: 2015

The BBCRS scheme is a variant of the McEliece public-key encryption scheme where the hiding phase is performed by taking the inverse of a matrix which is of the form $\mathbf{T} +\mathbf{R}$ where $\mathbf{T}$ is a sparse matrix with average row/column weight equal to a very small quantity $m$, usually $m < 2$, and $\mathbf{R}$ is a matrix of small rank $z\geqslant 1$. The rationale of this new transformation is the reintroduction of families of codes, like generalized Reed-Solomon codes, that are famously known for representing insecure choices. We present a key-recovery attack when $z = 1$ and $m$ is chosen between $1$ and $1 + R + O( \frac{1}{\sqrt{n}} )$ where $R$ denotes the code rate. This attack has complexity $O(n^6)$ and breaks all the parameters suggested in the literature.
Development of a multifactor authentication result checker system through GSM
Venue: arXiv cs.CY 2015
Year: 2015

This work is an implementation of a multifactor authentication SMS based result checking system. The objectives of this work were to improve on the available authentication methods and apply it on examination result checking system. The work takes care of only course codes with their grades, the current GPA and the overall CGPA. It employs the Pull SMS service, built on an independent service and a modem. Examination results consist of sensitive information, hence the need to further enhance the ones already in place so as to ensure further privacy and integrity, In the course of this project, the following assumptions were made: That a system that does the computation of students' result, calculate of GPA and CGPA is already in place. The implemented system was connected to the database of the existing system. A database that contains the bio-data of each student admitted exists. That SMTP (Simple Mail Transport Protocol) modem exists and should have been used but to reduce cost, a modem that can act like a SIM browser is used with a standard SIM card inserted in it and connected via cable to the application server. The system showed that further security and privacy could be achieved when multifactor authentication is employed. For further work, the system could be developed and built as a dependent service which involves having the application server connected to the service provider's SMS Center (SMSC). KEYWORDS Multifactor Authentication, GSM, Telecommunication, Communication, Internet.
Mind the Gap: Subspace based Hierarchical Domain Adaptation
Venue: arXiv cs.CV 2015
Year: 2015

Domain adaptation techniques aim at adapting a classifier learnt on a source domain to work on the target domain. Exploiting the subspaces spanned by features of the source and target domains respectively is one approach that has been investigated towards solving this problem. These techniques normally assume the existence of a single subspace for the entire source / target domain. In this work, we consider the hierarchical organization of the data and consider multiple subspaces for the source and target domain based on the hierarchy. We evaluate different subspace based domain adaptation techniques under this setting and observe that using different subspaces based on the hierarchy yields consistent improvement over a non-hierarchical baseline
Value Iteration with Options and State Aggregation
Venue: arXiv cs.AI 2015
Year: 2015

This paper presents a way of solving Markov Decision Processes that combines state abstraction and temporal abstraction. Specifically, we combine state aggregation with the options framework and demonstrate that they work well together and indeed it is only after one combines the two that the full benefit of each is realized. We introduce a hierarchical value iteration algorithm where we first coarsely solve subgoals and then use these approximate solutions to exactly solve the MDP. This algorithm solved several problems faster than vanilla value iteration.
Nonlinear Model Predictive Control of A Gasoline HCCI Engine Using Extreme Learning Machines
Venue: arXiv cs.SY 2015
Year: 2015

Homogeneous charge compression ignition (HCCI) is a futuristic combustion technology that operates with a high fuel efficiency and reduced emissions. HCCI combustion is characterized by complex nonlinear dynamics which necessitates a model based control approach for automotive application. HCCI engine control is a nonlinear, multi-input multi-output problem with state and actuator constraints which makes controller design a challenging task. Typical HCCI controllers make use of a first principles based model which involves a long development time and cost associated with expert labor and calibration. In this paper, an alternative approach based on machine learning is presented using extreme learning machines (ELM) and nonlinear model predictive control (MPC). A recurrent ELM is used to learn the nonlinear dynamics of HCCI engine using experimental data and is shown to accurately predict the engine behavior several steps ahead in time, suitable for predictive control. Using the ELM engine models, an MPC based control algorithm with a simplified quadratic program update is derived for real time implementation. The working and effectiveness of the MPC approach has been analyzed on a nonlinear HCCI engine model for tracking multiple reference quantities along with constraints defined by HCCI states, actuators and operational limits.
Exploring Green Interference Power for Wireless Information and Energy Transfer in the MISO Downlink
Venue: arXiv cs.IT 2015
Year: 2015

In this paper we propose a power-efficient transfer of information and energy, where we exploit the constructive part of wireless interference as a source of green useful signal power. Rather than suppressing interference as in conventional schemes, we take advantage of constructive interference among users, inherent in the downlink, as a source of both useful information and wireless energy. Specifically, we propose a new precoding design that minimizes the transmit power while guaranteeing the quality of service (QoS) and energy harvesting constraints for generic phase shift keying modulated signals. The QoS constraints are modified to accommodate constructive interference. We derive a sub-optimal solution and a local optimum solution to the precoding optimization problem. The proposed precoding reduces the transmit power compared to conventional schemes, by adapting the constraints to accommodate constructive interference as a source of useful signal power. Our simulation results show significant power savings with the proposed data-aided precoding compared to the conventional precoding.
Large deformation and post-failure simulations of segmental retaining walls using mesh-free method (SPH)
Venue: arXiv cs.CE 2015
Year: 2015

Numerical methods are extremely useful in gaining insights into the behaviour of reinforced soil retaining walls. However, traditional numerical approaches such as limit equilibrium or finite element methods are unable to simulate large deformation and post-failure behaviour of soils and retaining wall blocks in the reinforced soil retaining walls system. To overcome this limitation, a novel numerical approach is developed aiming to predict accurately the large deformation and post-failure behaviour of soil and segmental wall blocks. Herein, soil is modelled using an elasto-plastic constitutive model, while segmental wall blocks are assumed rigid with full degrees of freedom. A soft contact model is proposed to simulate the interaction between soil-block and block-block. A two dimensional experiment of reinforced soil retaining walls collapse was conducted to verify the numerical results. It is shown that the proposed method can simulate satisfactory post-failure behaviour of segmental wall blocks in reinforced soil retaining wall systems. The comparison showed that the proposed method can provide satisfactory agreement with experiments.
Efficient Algorithms for the Order Preserving Pattern Matching Problem
Venue: arXiv cs.DS 2015
Year: 2015

Given a pattern x of length m and a text y of length n, both over an ordered alphabet, the order-preserving pattern matching problem consists in finding all substrings of the text with the same relative order as the pattern. It is an approximate variant of the well known exact pattern matching problem which has gained attention in recent years. This interesting problem finds applications in a lot of fields as time series analysis, like share prices on stock markets, weather data analysis or to musical melody matching. In this paper we present two new filtering approaches which turn out to be much more effective in practice than the previously presented methods. From our experimental results it turns out that our proposed solutions are up to 2 times faster than the previous solutions reducing the number of false positives up to 99%
Categorified Reeb Graphs
Venue: arXiv cs.CG 2015
Year: 2015

The Reeb graph is a construction which originated in Morse theory to study a real valued function defined on a topological space. More recently, it has been used in various applications to study noisy data which creates a desire to define a measure of similarity between these structures. Here, we exploit the fact that the category of Reeb graphs is equivalent to the category of a particular class of cosheaf. Using this equivalency, we can define an `interleaving' distance between Reeb graphs which is stable under the perturbation of a function. Along the way, we obtain a natural construction for smoothing a Reeb graph to reduce its topological complexity. The smoothed Reeb graph can be constructed in polynomial time.
Real Time Collaborative Platform for Learning and Teaching Foreign Languages
Venue: arXiv cs.HC 2015
Year: 2015

The paper describes a novel social network-based open educational resource for learning foreign languages in real time from native speakers, based on the predefined teaching materials. This virtual learning platform, named i2istudy, eliminates misunderstanding by providing prepared and predefined scenarios, enabling the participants to understand each other and, as a consequence, to communicate freely. The system allows communication through the real time video and audio feed. In addition to establishing the communication, it tracks the student progress and allows rating the instructor, based on the learner's experience. The system went live in April 2014, and had over six thousand active daily users, with over 40,000 total registered users. Currently monetization is being added to the system, and time will show how popular the system will become in the future.
User involvement in the partner program of the educational social network
Venue: arXiv cs.HC 2015
Year: 2015

The paper describes experiments to attract active online system users to the partner program. The objective is to grow the number of users by involving existing system users in viral mechanics. Several examples of user motivation are given, along with the specific interface implementations and viral mechanics. Viral K-factor was used as the metrics for the resulting system growth assessment. Specific examples show both positive and negative outcomes. Growth of the target system parameters is discussed.
An optical image encryption scheme based on depth-conversion integral imaging and chaotic maps
Venue: arXiv cs.CR 2015
Year: 2015

Integral imaging-based cryptographic algorithms provides a new way to design secure and robust image encryption schemes. In this paper, we introduce a performance-enhanced image encryption schemes based on depth-conversion integral imaging and chaotic maps, aiming to meet the requirements of secure image transmission. First, the input image is decomposed into an elemental image array (EIA) by utilizing a pinhole array. Then, the obtained image are encrypted by combining the use of cellular automata and chaotic logistic maps. In the image reconstruction process, the conventional computational integral imaging reconstruction (CIIR) technique is a pixel-superposition technique; the resolution of the reconstructed image is dramatically degraded due to the large magnification in the superposition process as the pickup distance increases. The smart mapping technique is introduced to improve the problem of CIIR. A novel property of the proposed scheme is its depth-conversion ability, which converts original elemental images recorded at long distance to ones recorded near the pinhole array and consequently reduce the magnification factor. The results of numerical simulations demonstrate the effectiveness and security of this proposed scheme.
Second International Nurse Rostering Competition (INRC-II) --- Problem Description and Rules ---
Venue: arXiv cs.AI 2015
Year: 2015

In this paper, we provide all information to participate to the Second International Nurse Rostering Competition (INRC-II). First, we describe the problem formulation, which, differently from INRC-I, is a multi-stage procedure. Second, we illustrate all the necessary infrastructure do be used together with the participant's solver, including the testbed, the file formats, and the validation/simulation tools. Finally, we state the rules of the competition. All update-to-date information about the competition is available at http://mobiz.vives.be/inrc2/.
Retrospective Interference Alignment for the MIMO Interference Broadcast Channel
Venue: arXiv cs.IT 2015
Year: 2015

The degrees of freedom (DoF) of the multiple-input multiple-output (MIMO) Interference Broadcast Channel (IBC) with 2 cells and 2 users per cell are investigated when only delayed channel state information is available at the transmitter side (delayed CSIT). Retrospective Interference Alignment has shown the benefits in terms of DoF of exploiting delayed CSIT for interference, broadcast and also for the IBC. However, previous works studying the IBC with delayed CSIT do not exploit the fact that the users of each cell are served by a common transmitter. This work presents a four-phase precoding strategy taking this into consideration. Assuming that transmitters and receivers are equipped with $M,N$ antennas, respectively, new DoF inner bounds are proposed, outperforming the existing ones for $ρ= \frac{M}{N} > 2.6413$.
Optimal Signaling of MISO Full-Duplex Two-Way Wireless Channel
Venue: arXiv cs.IT 2015
Year: 2015

We model the self-interference in a multiple input single output (MISO) full-duplex two-way channel and evaluate the achievable rate region. We formulate the boundary of the achievable rate region termed as the Pareto boundary by a family of coupled, non-convex optimization problems. Our main contribution is decoupling and reformulating the original non-convex optimization problems to a family of convex semidefinite programming problems. For a MISO full-duplex two-way channel, we prove that beamforming is an optimal transmission strategy which can achieve any point on the Pareto boundary. Furthermore, we present a closed-form expression for the optimal beamforming weights. In our numerical examples we quantify gains in the achievable rates of the proposed beamforming over the zero-forcing beamforming.
Lower Bounds in the Preprocessing and Query Phases of Routing Algorithms
Venue: arXiv cs.DS 2015
Year: 2015

In the last decade, there has been a substantial amount of research in finding routing algorithms designed specifically to run on real-world graphs. In 2010, Abraham et al. showed upper bounds on the query time in terms of a graph's highway dimension and diameter for the current fastest routing algorithms, including contraction hierarchies, transit node routing, and hub labeling. In this paper, we show corresponding lower bounds for the same three algorithms. We also show how to improve a result by Milosavljevic which lower bounds the number of shortcuts added in the preprocessing stage for contraction hierarchies. We relax the assumption of an optimal contraction order (which is NP-hard to compute), allowing the result to be applicable to real-world instances. Finally, we give a proof that optimal preprocessing for hub labeling is NP-hard. Hardness of optimal preprocessing is known for most routing algorithms, and was suspected to be true for hub labeling.
Correntropy Induced L2 Graph for Robust Subspace Clustering
Venue: arXiv cs.CV 2015
Year: 2015

In this paper, we study the robust subspace clustering problem, which aims to cluster the given possibly noisy data points into their underlying subspaces. A large pool of previous subspace clustering methods focus on the graph construction by different regularization of the representation coefficient. We instead focus on the robustness of the model to non-Gaussian noises. We propose a new robust clustering method by using the correntropy induced metric, which is robust for handling the non-Gaussian and impulsive noises. Also we further extend the method for handling the data with outlier rows/features. The multiplicative form of half-quadratic optimization is used to optimize the non-convex correntropy objective function of the proposed models. Extensive experiments on face datasets well demonstrate that the proposed methods are more robust to corruptions and occlusions.